The present invention generally relates to optical fiber ribbons, and a die for making such ribbons. More specifically, the invention is directed to optical fiber ribbons that are color-coded for easy identification.
Optical fiber ribbons consist of a planar array of optical fibers joined together by a resin matrix material or the like. Such ribbons are becoming increasingly popular where optical fibers are used for data transmission and the like. This is due, in part, to the fact that optical fiber ribbons may contain a relatively large number of optical fibers in a package that allows for easy handling and installation. Further, because optical fiber ribbons reduce the need for manipulating individual optical fibers, optical fiber maintenance procedures are simplified. Often, a single cable will include numerous optical fiber ribbons, stacked one on another or otherwise disposed in the cable.
It is desirable to be able to easily identify and distinguish optical fiber ribbons one from another and to distinguish constituent elements of a given optical fiber ribbon, both before and after the ribbons are installed in the field for use. Conventionally, ribbon identification has been accomplished by printing characters, such as words, on the ribbon surface using ink jet printing methods. Often, such printing is accomplished in a process separate from the process for manufacturing the ribbon itself. In such cases, this additional step requires that the ribbon be handled, thus subjecting it to the risk of damage. Moreover, a separate and distinct printing step is time consuming and expensive. In some cases, the printing step may be combined with the ribbon manufacturing process.
Regardless of whether an on-line or off-line printing step is used, once the identifying characters have been printed on the ribbon (using ink jet methods or the like), the printed characters are susceptible to smearing. Such smearing may render the printed characters illegible. Even when the characters are not smeared, their small size makes it very difficult to read them, particularly in the field where lighting conditions tend to be poor. Also, matching particular printed characters (e.g., particular languages) to particular markets and/or customers can be a difficult and expensive task.
It is also known in the art to color-code optical fibers for the purpose of positively identifying individual fibers. Conventionally, a thermosetting ink layer, a UV-cured ink or varnish layer, or the like, is coated on the fiber to give it a particular color (see, e.g., U.S. Pat. Nos. 5,446,821 and 5,377,292, the disclosures of which are incorporated herein by reference). Alternatively, pigments or dyes or any other coloring agents can be directly mixed into the material used to coat the fiber as it is drawn from an optical fiber preform. Such methods eliminate the additional step required to apply the ink or varnish layer. Moreover, it is known to combine the processes of fiber coloring with ribbon manufacturing (see, e.g., Analysis of the Economics of On-line Colored Ribbon Manufacturing, by B. Arvidsson and J.Tanskanen, International Wire and Cable Symposium Proceedings 1996, pp. 566-569, the subject matter of which is incorporated herein by reference).
In one aspect, the present invention relates to an optical fiber ribbon that includes a plurality of substantially parallel, adjacent, longitudinally extending optical fibers disposed in substantially the same plane; at least one coating on each of the plurality of optical fibers; and a resin matrix material covering the optical fibers, wherein a color-coding identification scheme for the optical fiber ribbon is formed by coloring the ribbon with at least two colors. The resin matrix material forms an outer surface of the optical fiber ribbon, the outer surface including a top surface, a bottom surface, a first hinge (or edge), and a second hinge. At least a portion of the top surface is a different color from at least a portion of the bottom surface, the first hinge, and/or the second hinge. Further, at least a portion of the top surface and/or the bottom surface may be transparent or translucent. The resin matrix material itself may be colored with two or more dyes and/or pigments to form the color-coding identification scheme.
In another aspect, the present invention relates to an optical fiber ribbon that includes a plurality of substantially parallel, adjacent, longitudinally extending optical fibers disposed in substantially the same plane; at least one coating on each of the plurality of optical fibers; a plurality of sub-units that include a subset of the plurality of optical fibers, each sub-unit covered by a sub-unit resin matrix material; and a common resin matrix material covering the plurality of sub-unit resin matrix materials and forming an outer surface of the optical fiber ribbon, wherein a color coding identification scheme for the optical fiber ribbon is formed by coloring the ribbon with at least two colors. For example, at least one of the sub-unit resin matrix material and the common resin matrix material may be dyed or pigmented with at least two colors. The common resin matrix material forms an outer surface of the optical fiber ribbon, the outer surface including a top surface, a bottom surface, a first hinge, and a second hinge. At least a portion of the, top surface is a different color from at least a portion of the bottom surface, the first hinge, and/or the second hinge. At least a portion of the top surface and/or the bottom surface may be transparent or translucent. Further, at least a portion of the sub-unit resin matrix material may be transparent or translucent.
In yet another aspect, the present invention relates to a ribbon die for producing color-coded optical fiber ribbons such as those mentioned above, the ribbon die including at least one coating chamber having at least one primary coating orifice for supplying a primary coating material to be applied to the optical fibers; and at least one flow guide channel for supplying a colored material in addition to the primary coating material in order to coat predetermined areas of the fiber optic ribbon so as to form the color-coding identification scheme. The die may also include at least one removable insert in which the flow guide channel is formed.
These and other aspects, features, and advantages of the present invention will become more apparent in light of the detailed description of the preferred embodiments of the invention set forth below, considered together with the accompanying drawings (the features of which are not necessarily drawn to scale). In this regard, it is noted that like reference numerals/characters are used to identify like elements throughout the disclosure.